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A 2-Digit number is squared. When this 2-digit number is reversed and squared, the difference between the squares is also a square. What is the 2-digit number?

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The squares of any 8 consecutive numbers can be arranged into two sets of four numbers with the same sum. True of false?

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Order the Products

Age 14 to 16 Short
Challenge Level

Without calculating the five products below, put them in order of size, from smallest to largest. 

210$\times$190 198$\times$202 200$\times$200

195$\times$205 186$\times$214

This problem is taken from the World Mathematics Championships
You can find more short problems, arranged by curriculum topic, in our short problems collection.